Hello folks, I have a 1992 Ranger with the 4 cylinder 2.3 liter engine. I'm pretty sure the bolts that hold the exhaust on the head are 10mm. But does anyone out there know for sure what the pitch size is?

I am getting ready to install a new manifold. (My old manifold had a big crack in it). I figured I'd do the job right and clean the old bolts with a die. I've tried to measure with a caliper and seem to be getting around 1.50 mm or slightly more. However, when I try to turn a 10mm 1.50 pitch die around a bolt, I get quite a lot of resistance. I'm afraid to keep turning it. I've tried that on several of the bolts. They have some rust but otherwise don't look too bad.

Is this normal for bolts that have been on the truck for a while? I think quite possibly they've never been removed before.

Is it possible these bolts are some specialty size that available taps and dies won't work on?

Haven't tried tapping the head holes yet.

I've tried spinning a 10 mm 1.50 nut on a couple of the bolts just as a check. They go pretty nicely for the first few turns, but then get resistance.

I am correct that these would be metric, right? Not SAE? I thought most everything on the engine was metric.

 

Well nobody answered my post. But for the benefit of anyone else out there who might be searching for an answer to the same question:

After a lot of comparing and experimenting, I'm pretty satisfied the exhaust manifold bolts are in fact 10mm with 1.50 pitch. This is a 1992 Ranger, so my guess is that's probably the same for 1989 models through 1992. I went ahead and twisted a die around all of the bolts to clean them up anyway. There was some resistance. But after doing that job, they seem to be okay.They hold the manifold on just fine. I don't know how important it was to do that, but anyway I've done it.

I didn't tap out the holes though. Not quite brave enough to do that. But did chase the holes with a generic 10M 1.50 bolt that I have cut a groove in. Not much gunk came out anyway.

FYI if it helps anyone else, several years ago on another Ford Ranger I own (this one a 1989 with a 2.3 L) I installed an exhaust manifold I got from a junkyard. I re-used the original bolts and didn't do any die twisting. Just sprayed some carburetor cleaner on them and brushed them off some. And that truck is still running quietly, about 9 years and 80,000 miles so later.